Mechanism Research Of VIV Under The Influence Of Severe Slugging In Pipeline With The Gas And Liquid Mixture Transportation

With the gradual development of Chinese economy and the rapid growth of consumption of petroleum,more and more countries and regions are facing the challenge of energy shortage.Then more and more petroleum corporation concentrate on exploiting offshore oil field.The marine riser are important equipment of Exploitation of Offshore Petroleum.When oil field exploration grows into the advanced stage which has low liquid and gas flow rates,then it is easy to form liquid slug in the inclined tube which can block vapor enters the riser,and ultimately the severe slugging flow has formed.Large-amplitude pressure and flow rate fluctuation may occur in a pipeline-riser system.This article studies the vortex-induced of marine riser under the influence of severe slugging.First,it is need to transfer the three-dimensional pipeline-riser system to a two-dimensional pipeline-riser system by using equivalent method for saving a lot of time and computing resources.Four monitoring points for pressure inside the pipeline-riser system had been investigated at different eight different gas and liquid mass flow rates conditions by the use fluid dynamics simulation software of ANSYS Fluent.It found that the pressure drop of the pipeline is increase with the increase of gas velocity when the liquid velocity is 0.136m/s.The pressure drop in the pipeline is reduced with the liquid superficial velocity increase at the same gas velocity conditions.But severe slugging cycle time decreases with the increase of liquid velocity under the same gas velocity conditions,then the time required for the formation of severe slugging is less than ever.Secondly,a flow around a cylinder for lift and drag coefficients of variation had investigated by using ANSYS CFX.And the validity of the numerical model built need to be verified by compared the results with the classical theory.And vortex-induced vibration characteristics had been investigated at eight conditions for different velocity of fluid fields.VIV lift coefficient,drag coefficient and the direction Y axes of vibration under different outflow velocity had been investigated.Finally,the VIV variation characteristics under the influence of severe slug flow had been obtained by using GITT generalized integral transform method at eightdifferent outflow flow rates conditions.The fatigue life under severe slug flow and vortex-induced of marine riser had been calculated by using miner fatigue accumulation theory.It is useful for gas-liquid multiphase riser design and liabilities evaluation.